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Homework Help: Rotational Motion of a shaft

  1. Oct 29, 2009 #1
    1. The problem statement, all variables and given/known data
    A shaft is turning at 73.8 rad/s at time zero. Thereafter, its angular acceleration is given by
    a = -10.1 rad/s2 - 4.44 t rad/s3.
    where t is the elapsed time. Calculate its angular speed at t = 2.58 s

    2. Relevant equations
    1/2(Angular accel formula)+ 73.8t+0= theta final

    3. The attempt at a solution
    do i take the integral of the accel formula then the velocity the plug in 2.58?
  2. jcsd
  3. Oct 29, 2009 #2


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    You need to integrate both sides of

    dω = αdt

    The limits of integration should be

    73.8 to ω (left side) and 0 to 2.58 (right side)

    After you integrate, solve for ω.
  4. Oct 29, 2009 #3
    so i set 1/2(angular accel)= 73.8+ theta final? then take the integral?
  5. Oct 29, 2009 #4


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    I never said that. I have no idea where you get that 1/2(angular accel) = 73.8 + theta final means something when it is not even dimensionally correct. Do the following integral and solve for ω. That's what I suggested in the first place.

    [tex]\int_{73.8}^{\omega}d \omega=\int_{0}^{2.58}(-10.1-4.44 t) dt[/tex]
  6. Oct 29, 2009 #5
    whoa dude calm down. i appericiate the help but remember i was just asking a question, i already feel stupid enough as it is
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